Randomized clinical trial comparing conjugated equine estrogens and isoflavones in postmenopausal women: a pilot study

The aim of this study was to evaluate the effects of isoflavone on the climacteric symptoms (Kupperman Menopausal index), vaginal pH, vaginal cytology (vaginal maturation index) and endometrium (evaluated by ultrasound and biopsy) in postmenopausal women. It was a single-center, 6-month, randomized, double-blind, estrogen-controlled trial. Seventy-nine women were randomly assigned to one of the two treatment groups: isoflavone ( n = 40): 300 mg of the standardized soy extract with a medium dose of 120 mg isoflavones/day as glycoside and aglycone (60 mg twice a day), or estrogen ( n = 39): one capsule of 0.625 mg conjugated equine estrogens and other capsule with glucose 0.625 mg (placebo). After treatment, there was a decrease in the symptomatology in both estrogen and isoflavone groups. There was a significant decrease in vaginal pH, an increase in superficial vaginal cells and endometrium proliferation after 3 and 6 months of treatment in the estrogen group, but no differences were observed in the isoflavone group for these variables. We concluded that the daily standardized soy extract with 120 mg isoflavones’ effect on symptoms was similar to that from estrogen. Soy isoflavone has no effect on endometrium and vaginal mucosa during the treatment.